A gas turbine engine typically includes a compressor, a combustor, and a turbine. Airflow entering the compressor is compressed and directed to the combustor where it is mixed with fuel and ignited, producing hot combustion gases used to drive the turbine. Turbine engine performance and specific fuel consumption (SFC) are directly impacted by efficiency of compressors that are employed therein. Centrifugal compressors are commonly employed as the compressors to draw in and compress air, and the centrifugal compressors are the focus of various design improvements to increase the efficiency thereof. Improvements in centrifugal efficiency can be realized through various modifications such as optimization of impeller and diffuser design, particularly focusing upon vane configurations in both the impeller and the diffuser.
The diffuser vanes generally extend between a shroud and a hub in the centrifugal compressor, with the diffuser vanes, hub, and shroud defining flow channels for air provided by the impeller. The vanes are radially spaced about an outer circumference of the impeller and are generally designed to maximize aerodynamic flow and compression of the air. Angle and shape of diffuser vanes for maximum efficiency has been widely investigated, with certain modifications to diffuser vane configuration implemented to exploit a finding that a radial component of air discharge velocity varies across a discharge end of the impeller. In particular, it has been found that velocity of air is higher adjacent to a back wall of the impeller, i.e., adjacent to the hub, than at areas axially forward of the back wall, i.e., adjacent to the shroud. A twisted vane configuration has been proposed to align the diffuser vanes in a manner that more closely matches the flow profile of air that is provided by the impeller. The twisted vane configuration results in the diffuser vanes having a different angle at the shroud and at the hub. Despite advancements in diffuser vane design and configuration, there remains an opportunity to further refine diffuser vane designs and techniques for designing the diffuser vanes to maximize efficiency of the centrifugal compressors.
Accordingly, it is desirable to provide centrifugal compressors having twisted diffuser vanes, methods of forming the centrifugal compressors, and methods of designing diffuser vanes in centrifugal compressors that exhibit maximized efficiency. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.